Here Be Dragons

INTRODUCTION
difference, even with that giant's gaze. So if the Earth truly orbits the
Sun, even the nearest star must be incredibly, absurdly far away.
"Consequently I shall not speak now of the vast space between the orb
of Saturn and the Eighth Sphere [the fixed stars] left utterly empty of
stars by this reasoning," wrote Brahe. (And why did he "not speak" of
the thing he spoke of Because there was an even more persuasive argument
against Copernicus's theory: It was against the authority of
Holy Writ.)
But the stars are incredibly, absurdly far away—even the nearest
one. Proxima Centauri, an invisibly dim red star in the southern sky,
has that honor: it is 40,000,000,000,000 kilometers away from us.
Even if you could travel at the speed of light—which you couldn't—it
would be a four-and-a-quarter-year journey. The distance to Proxima
Centauri was figured out by the same method that failed the astronomers
of the sixteenth century. The idea was right, but the tools
weren't up to it. There were no telescopes.
And what about the farthest star For a long time the Milky Way
was the universe, and the farthest star was on the far side of it. But
then, in the 19205, came another shock, almost the equal of the one
delivered by the Polish canon. Fuzzy patches in the night sky proved to
be other "island universes," other galaxies. And galaxies assembled
themselves into clusters, and clusters into superclusters, and these in
turn receded to unfathomable distances. The farthest objects we have
observed lie about 100,000,000,000,000,000,000,000 kilometers
from Earth. 10 23 kilometers, to squeeze those zeroes to a superscript.
A i2-billion-year journey at the speed of light.
"The eternal silence of these infinite spaces frightens me," wrote
Blaise Pascal, when only the tiniest fraction of that truth was known.
What was the point of so much space Why, if the universe was made
for us, did it stretch so far beyond our reach What could one fill it
with, to take away its fearful emptiness, to give it purpose, human relevance,
warmth
Life!
The search for inhabited worlds began with Copernicus. Not that
the notion hadn't been around long before. Lucretius, the Roman disciple
of the Greek Atomists, spelled it out in the century before Christ:
"We must therefore admit again and again," he wrote, "that elsewhere
there are other gatherings of matter such as is this one which our sky
holds in its eager embrace.... Now if the atoms are so abundant that all
generations of living creatures could not count them, and if the same
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